The decomposition of the color photoresistant by the ultraviolet light and ozone system were investigated. The model compound, R, G, or B color photoresistant, was coated on a glass; then the formed film was exposured under an ultraviolet light, wavelength are 185 and 254 nm. The changes of the film thickness and morphology were determined and observed by a SEM, ATR-FTIR, and multichannel photodetector. It was found that the color photoresistant can be cleaned via decomposition under UV light and ozone in a short time. Based on the result, a UV-Ozone system was setup to clean the pollutant on the photo-mask. It is effective to clean photo-mask in less than 10 minutes under the dry process.